1. Field of the Invention
The present invention relates to a drilling apparatus for drilling a work such as a printed board and a thin board at a drilling mark attached to the work. In particular, the present invention concerns a drilling apparatus for receiving an image of a drilling mark of a work set on a working table by a camera unit, processing the image by an image processing unit and detecting the center of the target mark, and correctively moving a drill provided under the working table, thereby drilling the work at the center of the target mark.
2. Description of the Related Art
Conventionally, the drilling apparatus of this type has been known, for example in Examined Japanese Patent Publication No. SHO 64-11404. This drilling apparatus is operated by the steps of emitting a light to a drilling mark attached on a printed board by a spot light provided under a working table; receiving a transmission image by a camera unit; processing the image signal into a binary signal and displaying the enlarged binary image on a monitor; searching the binary image on the monitor by an image processing unit for detecting the center position of the drilling mark (binary image); and correctively moving a drill by an X/Y axis feed mechanism on the basis of the detection data, thereby drilling the printed board at the center of the drilling mark.
This prior art technique, however, fails to detect the drilling in the case where a work is molded of an opaque material.
The prior art drilling apparatus has the additional disadvantages as follows:
A large space under a working table is required to provide the spot light, resulting in the increased size of the drilling apparatus.
A work is subjected to thermal strain due to the radiation heat by the spot light. This deteriorates the accuracy in the detection of the center of the drilling mark.
Chips, which are produced during drilling, are scattered on the work, thereby reducing the drilling accuracy, and further, they are scattered around the drilling apparatus, thus exerting an adverse effect on the environment within the working room and on sanitary management.
The bulb of the spot light tends to be burnt out, which reduces the efficiency of the drilling operation.